Do-It-Yourself Clusters
Denis Sunko
Our research group recently bought a new, fourth node for our tiny cluster.
I added the following three lines into /etc/dhcpd.conf on the master node (see
Listing 1):
host osa4 {
hardware ethernet 00:c3:d4:e5:a1:b2;
fixed-address osa4;
}
("Osa" means wasp in Croatian.) Then we connected the new box with three wires:
power supply, patch cable to the Gigabit Ethernet switch, and null-modem cable
from its first serial port to the second serial port of the third box. We turned
on the power supply switch and were done, in principle. But I could not resist
making a show; I had connected by ssh to the third box and pointed minicom at
ttyS1, so we could watch the new node boot from the BIOS up. Of course, I knew
it would go smoothly, because everything was the same as with the other boxes
before it. Only a misprint in the hardware address above could have spoiled the
fun.
How did we make this happen? Lots of leisurely reading, stretched over two
months, and not much work, concentrated into several afternoons. This article
is a compression of that reading along with a little after-the-fact wisdom.
The configuration I will describe in this article is so simple, basic, and useful
that I hereby boldly proclaim -- it should be everybody's first cluster configuration.
Preventive Troubleshooting
You can do all the essential troubleshooting before even starting to shop
for equipment. To try out the configuration described in this article, you'll
need a Linux PC with an Ethernet port, a crossover cable, and a laptop. The
laptop does not need to have Linux installed, because it will become a stateless
slave node of the PC. It does, however, need the ability to boot over the network;
you can check for this in the BIOS setup or the documentation.
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